1. Field of the Invention
The present invention relates generally to a connecting scheme for a mobile communication system, and in particular, to a mobile communication system having a scheme for performing ATM-based connections between a controller and a transceiver subsystem of a base station, and between the base station and a mobile switching center.
2. Description of the Related Art
A typical mobile communication system includes a mobile switching center (MSC), a base station (BS) connected to the MSC by wire, and a mobile terminal or station (MT) with a wireless connection to the BS. The base station includes a base station controller (BSC) and a base station transceiver subsystem (BTS).
In the conventional mobile communication system, a synchronous transfer mode (STM) or a connectionless packet transfer mode is used for the connection between the mobile switching center and the base station controller and the connection between the base station controller and the base station transceiver subsystem. Therefore, when connecting the mobile switching center to the base station controller or connecting the base station controller to the base station transceiver subsystem using a plurality of physical links, it can happen that the traffic becomes concentrated on just one of the physical links, thereby reducing the utilization efficiency of the overall system.
In addition, in the STM system, each channel band (i.e., time slot) is assigned to a specific source for transmitting the traffic. Therefore, when the source has no traffic to transmit, the corresponding channel remains empty and this empty channel cannot be used by other sources. This reduces traffic transmission efficiency.
In the near future, mobile communication systems will provide multimedia traffic services including voice, data and image information. Voice, data and image information have different QoS (Quality of Service) requirements with respect to data loss and transmission delay, and it is necessary to process the traffic according to these QoS requirements. For example, with regard to voice transmission, the service quality is not greatly affected by minor data loss, but is drastically degraded when transmission delay occurs. On the contrary, with regard to data transmission, the service quality is not greatly affected by transmission delay, but is very susceptible to the effects of data loss. However, in the STM or connectionless packet transfer mode mobile communication system, it is not easy to manage the service quality according to the type of media or type of traffic so that it is not possible to provide optimal service quality for each of the respective media.